// DeflaterStaticFields.cs
//
// Copyright (C) 2001 Mike Krueger
// Copyright (C) 2004 John Reilly
// Copyright (C) 2010 Thomas Maierhofer

//
// (2010) This Code was modified from SharpZipLib http://www.icsharpcode.net/OpenSource/SharpZipLib/  
// to fit the needs of Second WAF - a heavy load web application framework 
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 2001 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
// 
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module.  An independent module is a module which is not derived from
// or based on this library.  If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so.  If you do not wish to do so, delete this
// exception statement from your version.


namespace WAF.Content
{
    using System;
    public partial class Deflater
    {
        /// <summary>
        /// Compressed Blocks Length Codes (3.2.5)
        /// </summary>
        struct BlockLengthCodes 
        {
            public short LengthCode; // 0-255 Literal Values, 256 = End of Block, 257-285 = length codes
            public ushort ExtraBits;
            public ushort ExtraBitsCode;
        }

        struct BlockDistanceCodes
        {
            public short DistanceCode;
            public ushort ExtraBits;
            public ushort ExtraBitsCode;
        }

        #region Public Constants
        /// <summary>
        /// The best and slowest compression level.  This tries to find very
        /// long and distant string repetitions.
        /// </summary>
        public const int BEST_COMPRESSION = 9;

        /// <summary>
        /// The worst but fastest compression level.
        /// </summary>
        public const int BEST_SPEED = 1;

        /// <summary>
        /// The default compression level.
        /// </summary>
        public const int DEFAULT_COMPRESSION = -1;

        /// <summary>
        /// This level won't compress at all but output uncompressed blocks.
        /// </summary>
        public const int NO_COMPRESSION = 0;

        /// <summary>
        /// The compression method.  This is the only method supported so far.
        /// There is no need to use this constant at all.
        /// </summary>
        public const int DEFLATED = 8;
        #endregion

        const int BUFSIZE = 1 << (DEFAULT_MEM_LEVEL + 6);

        // Number of static Literal codes (3.2.6)
        const int STATIC_LITERAL_CODES_NUMBER = 286;

        // Number of static distance codes (3.2.6)
        const int STATIC_DISTANCE_CODES_NUMBER = 30;

        // Number of codes used to transfer bit lengths
        const int BITLEN_NUM = 19;

        // repeat previous bit length 3-6 times (2 bits of repeat count)
        const int REP_3_6 = 16;
        // repeat a zero length 3-10 times  (3 bits of repeat count)
        const int REP_3_10 = 17;
        // repeat a zero length 11-138 times  (7 bits of repeat count)
        const int REP_11_138 = 18;

        const int EOF_SYMBOL = 256;

        const int LENGTH_CODE_NUM = 256;
        const int DISTANCE_CODE_NUM = 32768;


        // The lengths of the bit length codes are sent in order of decreasing
        // probability, to avoid transmitting the lengths for unused bit length codes.
        static readonly int[] BL_ORDER = { 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };

        static readonly byte[] nibbleReverse = {
			0,
			8,
			4,
			12,
			2,
			10,
			6,
			14,
			1,
			9,
			5,
			13,
			3,
			11,
			7,
			15
		};

        static readonly uint[] CrcTable = new uint[] {
			0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419,
			0x706AF48F, 0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4,
			0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07,
			0x90BF1D91, 0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE,
			0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, 0x136C9856,
			0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9,
			0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4,
			0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
			0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3,
			0x45DF5C75, 0xDCD60DCF, 0xABD13D59, 0x26D930AC, 0x51DE003A,
			0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599,
			0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
			0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190,
			0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F,
			0x9FBFE4A5, 0xE8B8D433, 0x7807C9A2, 0x0F00F934, 0x9609A88E,
			0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
			0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED,
			0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950,
			0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3,
			0xFBD44C65, 0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2,
			0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A,
			0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5,
			0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA, 0xBE0B1010,
			0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
			0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17,
			0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6,
			0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615,
			0x73DC1683, 0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8,
			0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1, 0xF00F9344,
			0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB,
			0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A,
			0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
			0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1,
			0xA6BC5767, 0x3FB506DD, 0x48B2364B, 0xD80D2BDA, 0xAF0A1B4C,
			0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF,
			0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
			0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE,
			0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31,
			0x2CD99E8B, 0x5BDEAE1D, 0x9B64C2B0, 0xEC63F226, 0x756AA39C,
			0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
			0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B,
			0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242,
			0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1,
			0x18B74777, 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C,
			0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45, 0xA00AE278,
			0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7,
			0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC, 0x40DF0B66,
			0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
			0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605,
			0xCDD70693, 0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8,
			0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B,
			0x2D02EF8D
		};

        static HuffmanTree.Symbol[] staticLiteralSymbols; // RFC 1950 3.2.6 - Fixed Literal Codes
        static HuffmanTree.Symbol[] staticDistanceSymbols; // RFC 1950 3.2.6 - Fixed Distance Codes
        static BlockLengthCodes[] staticBlockLengthCodes;   // RFC 1950 3.2.5 - length codes
        static BlockDistanceCodes[] staticBlockDistanceCodes;   // RFC 1950 3.2.5 - distance codes

        static HuffmanTree.Symbol[] staticZLibHeaderFast; // RFC 1950 2.2 - Header fast compression
        static HuffmanTree.Symbol[] staticZLibHeaderSlow; // RFC 1950 2.2 - Header slow compression

        static HuffmanTree.Symbol[] staticGZipHeaderFast; // RFC 1952 2.3 - Header fast compression
        static HuffmanTree.Symbol[] staticGZipHeaderSlow; // RFC 1952 2.3 - Header slow compression

        static Deflater()
        {
            // See RFC 1951 3.2.6
            // Literal codes
            staticLiteralSymbols = new HuffmanTree.Symbol[STATIC_LITERAL_CODES_NUMBER];

            uint i = 0;
            while (i < 144)
            {
                staticLiteralSymbols[i].BitsCode = BitReverse((0x030 + i) << 8);
                staticLiteralSymbols[i++].Bits = 8;
            }

            while (i < 256)
            {
                staticLiteralSymbols[i].BitsCode = BitReverse((0x190 + i - 144) << 7);
                staticLiteralSymbols[i++].Bits = 9;
            }

            while (i < 280)
            {
                staticLiteralSymbols[i].BitsCode = BitReverse((0x000 + i - 256) << 9);
                staticLiteralSymbols[i++].Bits = 7;
            }

            while (i < STATIC_LITERAL_CODES_NUMBER)
            {
                staticLiteralSymbols[i].BitsCode = BitReverse((0x0c0 + i - 280) << 8);
                staticLiteralSymbols[i++].Bits = 8;
            }

            // Distance codes

            staticDistanceSymbols = new HuffmanTree.Symbol[STATIC_DISTANCE_CODES_NUMBER];
            for (i = 0; i < STATIC_DISTANCE_CODES_NUMBER; i++)
            {
                staticDistanceSymbols[i].BitsCode = BitReverse(i << 11);
                staticDistanceSymbols[i].Bits = 5;
            }

            
            // Block Length Code Precalc (3.2.5)
            staticBlockLengthCodes = new BlockLengthCodes[LENGTH_CODE_NUM];
            for (i = 0; i < LENGTH_CODE_NUM; ++i)
            {
                staticBlockLengthCodes[i].LengthCode = (short) LengthCode((int) i);
                staticBlockLengthCodes[i].ExtraBits = (ushort)((staticBlockLengthCodes[i].LengthCode - 261) / 4);
                staticBlockLengthCodes[i].ExtraBitsCode = (ushort) (i & ((1 << (staticBlockLengthCodes[i].ExtraBits)) - 1));
                if (!(staticBlockLengthCodes[i].LengthCode >= 265 && staticBlockLengthCodes[i].LengthCode < 285))
                    staticBlockLengthCodes[i].ExtraBits = 0;
            }

            // Block Distance Code Precalc (3.2.5)
            staticBlockDistanceCodes = new BlockDistanceCodes[DISTANCE_CODE_NUM];
            for (i = 0; i < DISTANCE_CODE_NUM; ++i)
            {
                staticBlockDistanceCodes[i].DistanceCode= (byte) DistanceCode((int) i);
                staticBlockDistanceCodes[i].ExtraBits = (byte)(staticBlockDistanceCodes[i].DistanceCode / 2 - 1);
                staticBlockDistanceCodes[i].ExtraBitsCode = (ushort)(i & ((1 << staticBlockDistanceCodes[i].ExtraBits) - 1));
                if (i <= 3)
                    staticBlockDistanceCodes[i].ExtraBits = 0;

            }

            staticZLibHeaderFast = new HuffmanTree.Symbol[2];
            staticZLibHeaderFast[0].Bits = 8;
            staticZLibHeaderFast[0].BitsCode = 120; // CM=8, CINFO=7
            staticZLibHeaderFast[1].Bits = 8;
            staticZLibHeaderFast[1].BitsCode = 1; // FCHECK = 1, FDICT=false, FLEVEL=0

            staticZLibHeaderSlow = new HuffmanTree.Symbol[2];
            staticZLibHeaderSlow[0].Bits = 8;
            staticZLibHeaderSlow[0].BitsCode = 120; // CM=8, CINFO=7
            staticZLibHeaderSlow[1].Bits = 8;
            staticZLibHeaderSlow[1].BitsCode = 192; // FCHECK = 0, FDICT=false, FLEVEL=7 


            staticGZipHeaderFast = new HuffmanTree.Symbol[8];
            staticGZipHeaderFast[0].Bits = 8;
            staticGZipHeaderFast[0].BitsCode = 31; // ID1

            staticGZipHeaderFast[1].Bits = 8;
            staticGZipHeaderFast[1].BitsCode = 139; // ID2

            staticGZipHeaderFast[2].Bits = 8;
            staticGZipHeaderFast[2].BitsCode = 8; // CM8 = Deflate

            staticGZipHeaderFast[3].Bits = 8;
            staticGZipHeaderFast[3].BitsCode = 0; // FLAGS

            staticGZipHeaderFast[4].Bits = 16;
            staticGZipHeaderFast[4].BitsCode = 0; // MTIME

            staticGZipHeaderFast[5].Bits = 16;
            staticGZipHeaderFast[5].BitsCode = 0; // MTIME

            staticGZipHeaderFast[6].Bits = 8;
            staticGZipHeaderFast[6].BitsCode = 4; // XFL fastest algorithm

            staticGZipHeaderFast[7].Bits = 8;
            staticGZipHeaderFast[7].BitsCode = 255; // OS = Unknown
        }

        /// <summary>
        /// Length Code according to RFC 1951 - 3.2.5
        /// </summary>
        /// <param name="length">The length - 3 (3 = 0, 258 = 255)</param>
        /// <returns>the length code for the specified length</returns>
        static int LengthCode(int length)
        {
            if (length == 255)
            {
                return 285;
            }

            int code = 257;
            while (length >= 8)
            {
                code += 4;
                length >>= 1;
            }
            return code + length;
        }

        /// <summary>
        /// Distance  Code according to RFC 1951 - 3.2.5
        /// </summary>
        /// <param name="distance">The distance -1. (1=0, 32768=32767</param>
        /// <returns>the distance code for the specified distance</returns>
        static int DistanceCode(int distance)
        {
            int code = 0;
            while (distance >= 4)
            {
                code += 2;
                distance >>= 1;
            }
            return code + distance;
        }
    }
}
